Micro-architectured structures, or “microstructures,” including microlattices and microsandwiches, have recently emerged as promising structural and functional frameworks for small-scale multi-functional devices. The open architecture of such structures not only leads to low areal density and high damage tolerance, but also provides channels for heat and fluid flow, which are critical to multi-functional devices, such as high capacity batteries, insect-like robots, and micro-air vehicles.
Sandwich structures, which comprise a core that extends between opposed end plates, exhibit higher bending rigidity than lattices by effectively redistributing the mass to the outer surfaces (instead of the core), similar to natural cellular materials found in insects and plants. Such superior properties have led to extensive studies on the structural performance of sandwich structures, mostly with physical dimensions above tens of centimeters. The damage tolerance of sandwich structures is highly dependent on the density, strength, and geometry of the core. It was found that a periodic sandwich core can be optimized to sustain loads at much lower relative densities than stochastic foams. Further improvement of mechanical properties may also be achieved by hybridizing the core material.
Existing fabrication procedures for large-scale sandwich structures typically involve welding or adhesive bonding of the face sheets and the core. These techniques become challenging as the size of the sandwich's core decreases to the nano- or micro-scale. Recently there have been several successful attempts to create microlattice and microsandwich structures from polymers, ceramics, and metals. Unfortunately, the fabrication processes used to construct these microstructures are complicated or limited to specific materials. It can therefore be appreciated that it would be desirable to have a more simple fabrication technique for such microstructures.